Speed governor for an engine having an electronic fuel injection system

ABSTRACT

Apparatus for use with an engine having an electronic fuel injection (EFI) system, and which apparatus governs engine speed to a predetermined set point. Engine speed is sensed and regulates the fuel supply to the engine whereupon fuel pressure is used as an actuating force to remove engine throttle commands from the control of the operator when the engine speed reaches the set point.

United States Patent Rachel 1 1 SPEED GOVERNOR FOR AN ENGINE HAVING AN ELECTRONIC FUEL INJECTION SYSTEM [75] Inventor: Todd L. Rachel, Rochester, Mich.

[73] Assignee: The Bendix Corporation, Teterboro,

[22] Filed: July 2, 1973 [21] App1.No.:375,580

[ 52] U.S. C1. 123/102; 123/106; 123/32 EA [51] Int. Cl B60k 31/00 [58] Field of Search 123/106, 102, 32 EA [56] References Cited UNITED STATES PATENTS 3,099,330 7/1963 Von Berg et a1. 123/102 3,601,103 8/1971 Swiden 3,648,798 3/1972 Jania 123/102 ELECTRONIC CONTROL P'CKUP UNIT TO ENGINE 27 FREQUENCY TO DC CONVERTER EFI SYSTEM June 17, 1975 3,651,460 3/1972 Gebelein 123/102 3,702,603 11/1972 Baxendale... 123/102 123/102 3,745,982 7/1973 Suda et a1 Primary ExaminerManuel A. Antonakas Assistant Examiner-Joseph Cangelosi Attorney, Agent, or FirmAnthony F. Cuoco; S. H. Hartz 57} ABSTRACT 'the control of the operator when the engine speed reaches the set point.

2 Claims, 5 Drawing Figures FUEL 90 PROPORTIONAL SOLENOID THROTTLE BODY THROTTLE 4s TANK RETURN as j as o FUNCTION GENERATOR PATENTEDJUN 17 I975 SHEET ENGINE LINKAGE 1.. THROTTLE E F E WR O Y T0 I. m M T I? E T P m m Ms a M w. MRW .lllTMN C U C L E GP m 0. Wm P SPEED GOVERNOR FOR AN ENGINE HAVING AN ELECTRONIC FUEL INJECTION SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to the field of electronic fuel injection (EFI) systems and particularly to EFI systems for automotive type internal combustion engines. More particularly, an improved engine speed governor is provided which uses EFI system fuel pressure to govern engine speed to a predetermined set point.

2. Description of the Prior Art It is often desirable, for commercial type motor vehicles, to govern engine speed to a predetermined set point. When electronic fuel injection systems are used in the engines of these vehicles it is advantageous to utilize EFI parameters for achieving speed governing characteristics and minimize the auxilliary equipment required. The present invention uses existing sensed parameters and by means of an electrohydraulic transducer uses EFI system fuel pressure as an actuating force to remove, through existing throttle linkages, engine throttle commands from the driver when the engine rpm reaches the set point, so as to be an improvement over prior art devices.

SUMMARY OF THE INVENTION This invention contemplates an engine speed governor for use with an electronic fuel injection system wherein, in one embodiment of the invention, engine speed is sensed and converted to a dc. signal. A comparator compares the dc signal to a dc. signal corresponding to a predetermined speed set point and develops an error signal which is amplified and operates a proportional solenoid for regulating fuel flow to an engine throttle actuator in order to close the throttle plates when engine speed reaches the set point. In another embodiment of the invention engine speed actuates a flip-flop in the electronic control unit (ECU) of the EFI system, which provides pulses at a frequency commensurate with engine speed. This frequency is compared to a frequency corresponding to the predetermined speed set point and the error frequency actuates an intermittent fuel flow regulating valve for sufficient time in each engine cycle to power and hold the engine throttle to the desired position to maintain the set point speed. The invention operates in open loop configuration. The first mentioned embodiment provides analog or continuous control while the second embodiment provides digital or intermittent control.

The foregoing and other objects and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein several embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for illustration purposes only and are not to be construed as defining the limits of the invention.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic representation of an electronic fuel injection system for an internal combustion engine with which the engine speed governor of the present invention may be used.

FIG. 2 is a diagrammatic representation of an engine throttle mechanism associated with the engine speed governor of the invention.

FIG. 3 is a schematic representation of one embodiment of the engine speed governor according to the invention.

FIG. 4 is a schematic representation of another embodiment of the speed governor according to the invention.

FIG. 5 is a graphical representation showing pulse waveforms provided by the embodiment of the invention according to FIG. 4.

DESCRIPTION OF THE INVENTION Referring first to FIG. 1, an electronic fuel injection system is shown with which the present invention may be utilized. The system is comprised of an electronic control unit 10 which receives signals from a timing pick-up 12, a temperature sensor 14 and various parameter sensors 16 associated with a throttle body 20.

Timing pick-up 12 provide signals indicative of engine speed. These signals may be derived from any source indicative of engine crank angle but are preferably from the engine ignition distributor. Parameter sensors 16 are attached to throttle body 20 which controls the flow of air into an engine 27. Throttle body 20 has a pair of air passages passing therethrough indicated as 22 and the effective cross-sectional area of passages 22 is controlled by throttle plates 24. Throttle plates 24 are mounted on a shaft 26 for controlled rotation there with. The angular position of shaft 26 and hence of throttle plates 24 is controlled by throttle control means comprised of a linkage 18 and a pedal 28 connected thereto through suitable connecting means 30.

Electronic control unit 10 is energized by a battery 32 which may be the vehicle battery and which also energizes those of the various sensors which require external energization. The output of electronic control unit 10 controls the energization of an injector valve means 34 which is mounted in the intake manifold 36 of engine 27 and which is adapted to introduce an airfuel mixture for intake through intake valve 38, shown in open position, into the combustion cylinder 40 of the engine. Pressurized fuel is provided to injector valve 34 from fuel tank 42 by means of a pump 44 and suitable fuel supply and return lines 46. It is well known in the art that computing means 10 may control an injector valve means comprised of one or more injector valve members 34 arranged to be actuated singly or in groups of varying numbers in sequential fashion as well as simultaneously.

Throttle linkage 18, which may be of the type shown for purposes of illustration in FIG. 2, includes a housing member 60, lost motion link 62, resilient biasing means 64, position control means 66, and closing means 70. Lost motion link 62 is fixedly attached to throttle plate shaft 26 to control rotation thereof. Lost motion link 62 includes a travel slot 72 and position control means 66 includes a pin member 74 mounted for movement in travel slot 72. Resilient means 64 is operative to urge pin member 74 to an extreme end of slot 72 while position control means 66 is operative to urge the pin towards the other extreme end of slot 72. Closing means 70 is operative to urge the lost motion link and, hence, throttle plates 24, counterclockwise relative to the drawing of FIG. 2 to effect closing movement thereof upon release of tension in control means 66.

In operation, with throttle plate 24 at any angular position indicative of the engine operating situation, the application of pressure to throttle pedal 28 (FIG. 1) will cause, through means 30, a rightward (relative to FIG. 2) movement of control means 66. However, the initial movement of position control means 66 will cause pin 74 to move rightward with slot 72 against the bias of resilient means 64 prior to any movement of throttle plates 24. This can readily be arranged by insuring that the initial increment of movement of resilient means 64 requires less force than does movement of'lost motion link 62 against the bias of closing means 70 and any friction present in the amount of shaft 26.

With reference now to FIG. 3, wherein one embodiment of the invention is shown and used in conjunction with the apparatus described with reference to FIGS. 1 and 2, timing pick-up 12 provides alternating signals at a frequency corresponding to the speed of engine 27. The signals are applied to a conventional frequency to d.c. converter 80 which provides a corresponding d.c. signal.

A d.c. signal source 82, which may be a battery, provides a d.c. signal corresponding to a predetermined desired set point speed. The signals from d.c. signal source 82 and frequency to d.c. converter 80 are compared by a comparator amplifier 84 which provides an error signal V corresponding to the difference between the compared signals.

Signal V. from comparator 84 is applied to function generator 86 which provides a signal V related to signal V in accordance with the graphical illustration designated a in FIG. 3. Signal V is amplified by an amplifier 88 and applied therefrom to a proportional solenoid 90. Solenoid 90 actuates a flow modulator 92, which may be of the flexible diaphragm type, to regulate the pressurized fuel flow through supply and return lines 46A to a throttle actuator 45 which may be a conventional servo type device. The fuel pressure provided by the regulated fuel flow is applied by actuator 45 as an actuating force to close throttle plates 24 (FIGS. 1 and 2) until the engine speed reaches the predetermined set point, thereby removing speed control from the driver of the vehicle as provided through foot pedal 28.

With reference to FIG. 4, wherein an alternate embodiment of the invention is shown, the signals from timing pick-up l2 actuate a flip-flop 100 in electronic control unit for providing a pulse V having a waveform as shown in FIG. 5. Pulse V,- has a width T and has equally spaced transitions at a given engine speed.

Pulse V,- is applied to a conventional type frequency comparator 102 where the frequency thereof is compared with the frequency of a pulse V, from a pulse source 104 which may be a conventional type oscillator. Pulse V,- has a waveform as shown in FIG. 5, with transitions corresponding to the desired set point speed. Pulse V has a pulse width T and is synchronized with pulse V,- as shown in the figure.

The output of frequency comparator 102 is a pulse V having a width T which is the difference between pulse widths T, and T when T, is, for example, less than T as shown in the figure. Pulse V is modulated by a pulse width modulator 106 and the modulator pulse is applied to an intermittent on-off valve 108 which regulates the pressurized fuel flow through supply and return lines 46A to throttle actuator 45 for a sufficient time in each engine cycle to power and hold throttle plates 24 (FIG. 1) to the desired position for maintaining the predetermined set point engine speed.

In summary, then, there is described means for governing engine speed to a predetermined set point. The speed may be governed in a continuous or analog fashion as described with reference to FIG. 3 or in an intermittent or digital fashion as described with reference to FIG. 4. The invention has been described for use with an engine having an electronic fuel control system so as to utilize engine parameter sensors included therein, and specifically to use regulated fuel flow pressure as an actuating force to provide the speed governing characteristic. It will be understood, however, .that the speed governor described may be used with a conventional internal combustion engine as well.

In this connection it is noted that the invention is especially cost effective when used with an EFI system since the necessary parameters are already sensed and provided in an electronic format, and the EFI system employs a pressurized fuel supply which may be used as a throttle actuating force as described. Alternatively, air pressure or oil pressure may be used as well.

To these ends it is to be understood that although several embodiments of the invention are illustrated and described in detail the invention is not limited thereto. Various changes may also be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. In an internal combustion engine including a fuel control system of the type having sensor means including means for generating an ac. signal at a frequency corresponding to engine speed, responsive to engine conditions operative to provide signals indicative of engine generating parameters, means responsive to the sensor means signals operative to provide a fuel delivery command signal indicative of the engine fuel requirements, fuel supply means responsive to the fuel delivery command signal operative to supply the engine with pressurized fuel in relation to the fuel delivery command signal and means for controlling mixture of fuel and air to the engine, the improvement comprising:

means for providing a d.c. signal corresponding to a predetermined set point speed;

a converter connected to the a.c. signal generating means for converting the engine speed signal therefrom to a d.c. signal;

means for comparing the d.c. set point speed signal and the d.c. engine speed signal and for providing an error signal;

means connected to the error signal means for providing a signal as a function of the error signal, the function signal being at a constant level when the error signal is in one sense and increasing linearly when the error signal is in an opposite sense;

fuel regulating means connected to the function signal means and to the fuel supply and responsive to the function signal for regulating said fuel supply, said regulated fuel supply providing a force; and

actuator means connected to the fuel regulating means and to the mixture control means and responsive to said force for actuating the mixture control means to control the mixture of air and fuel to the engine to maintain the predetermined set point speed.

a supply of pressurized fluid;

regulating means including on-off flow valve means connected to the fluid supply and to the pulse width modulator and responsive to the modulated pulse for permitting pressurized fluid from the supply for a sufficient time to provide a force; and

actuator means connected to the regulating means and to the mixture control means and responsive to said force for actuating the mixture control means to control the mixture of air and fuel to the engine to maintain the predetermined set point speed. 

1. In an internal combustion engine including a fuel control system of the type having sensor means including means for generating an ac. signal at a frequency corresponding to engine speed, responsive to engine conditions operative to provide signals indicative of engine generating parameters, means responsive to the sensor means signals operative to provide a fuel delivery command signal indicative of the engine fuel requirements, fuel supply means responsive to the fuel delivery command signal operative to supply the engine with pressurized fuel in relation to the fuel delivery command signal and means for controlling mixture of fuel and air to the engine, the improvement comprising: means for providing a d.c. signal corresponding to a predetermined set point speed; a converter connected to the a.c. signal generating means for converting the engine speed signal therefrom to a d.c. signal; means for comparing the d.c. set point speed signal and the d.c. engine speed signal and for providing an error signal; means connected to the error signal means for providing a signal as a function of the error signal, the function signal being at a constant level when the error signal is in one sense and increasing linearly when the error signal is in an opposite sense; fuel regulating means connected to the function signal means and to the fuel supply and responsive to the function signal for regulating said fuel supply, said regulated fuel supply providing a force; and actuator means connected to the fuel regulating means and to the mixture control means and responsive to said force for actuating the mixture control means to control the mixture of air and fuel to the engine to maintain the predetermined set point speed.
 2. In an internal combustion engine of the type including means for controlling the mixture of fuel and air to the engine, the improvement comprising: means for providing pulses at a frequency corresponding to engine speed; means for providing pulses at a frequency corresponding to a predetermined set point speed; means for comparing said frequencies and for providing a pulse at a frequency which is the difference between the compared frequencies; a pulse width modulator connected to the frequency comparing means for modulating the width of the pulse therefrom; a supply of pressurized fluid; regulating means including on-off flow valve means connected to the fluid supply and to the pulse width modulator and responsive to the modulated pulse for permitting pressurized fluid from the supply for a sufficient time to provide a force; and actuator means connected to the regulating means and to the mixture control means and responsive to said force for actuating the mixture control means to control the mixture of air and fuel to the engine to maintain the predetermined set point speed. 